Riveting machine



June 10, 1941. m VENER 2,244,878

RIVETING MACHINE Filed March 10, 1937 4 Sheets-Sheet l June 10, 1941 l iL i c) O A. R. HAVEN ER RIVETING MACHINE Filed March 10, 1937 4 Sheets-Sheet 2 7 rave/70507.

Ckm mv June 10, 1941 VE R 2,244,878

RIVETING MACHINE Filed March 10, 1937 4 Sheets-Sheet 4 Patented June 10, 1941 '1 OFFICE mvarmo MACHINE Arthur R. Havener, Wayland, Mass, assignor to Judson L. Thomson Manuiacturing Company, Waltham, Mass, a corporation of Massachu' setts Application March 10, 1937, Serial No. 130,021 j 11 Claims.

This invention relates to riveting machines and more particularly to a machine of that character adapted for driving and. clinching rivets having extremely long shanks, such as are used, for instance, in fastening together wooden chair parts.

In the manufacture of riveting machines designed for rivets of the foregoing character, great difiiculty has been experienced in providing means for so controlling the movement of the rivets through theholder as to prevent lateral movement thereof and to insure straight driving. Rivets of this character are used to a large extent in fastening together parts of wooden chairs, which parts are prepared with holes for holding the rivets. In this work, thetwo parts to be fastened together are adjusted in the machine with the spindle of the anvil in the aligned holes, but if either part is warped slightly, the hole in the top part is thrown out of exact register with the end of the rivet. In such a case, if there is any lateral movement of the shank of the rivet as it emerges from the holder, the end of the rivet as it is driven is apt to be deflected laterally and to split. the chair parts. Sometimes this results in breaking off the spindle of-the machine.

One of the important objects of the invention is the provision of a riveting machine of very simple yet eihcient' and durable construction.

Another important object of my invention is the provision in a riveting machine of rivet driving and rivet holding means which so controlthe movement of long shank rivets through the holder that straight driving of the rivets is at all times absolutely assured.

A further object of the invention is the provision ofsimple and efiicient means in a riveting machine for producing differential movements of the rivet driving and the. rivet holding means without requiring the use of cams or other complicated mechanisms.

Other objects of the invention will be more specifically described hereinafter.

One of the important features of the invention resides in a rivet holder so constructed as to insure th'ata rivet being driven through and out held together by spring pressure exerted midway their ends. When the two jaws are in engagement with each other, the diameter of the chamber is slightly less than the diameter of the head of the rivet. The top end of the chamber expands outwardly for holding afrivet suspended by its head in position for driving, and the bottom end of the chamber is restricted to an opening oi smaller diameter than the diameter of the shank of the rivet. When the rivet is forced downwardly between the jaws, its; head opens or separates the jaws at their upper ends against the spring pressure, and, as the shank passes out through the bottom opening; it has the same effect on' the lower endsof the jaws. As a result, a continuous pressure is exerted by the jawsozrthe head of the rivetand on its shank as it emerges ,from the jaws; which pressure is sufficient to prevent any lateral deflection of the shank and to insure straight driving; g V

Another important feature of my invention resides in the provision of simple means' for pro.- ducing differential movements of the rivet driver and the rivet holder, whereby the rivet driver first moves downwardly close to the. head of the. rivet in the holder, whereupon the holder moves in unison with the driver until it is close to the work,

whereupon it stops and the driver continues its downward .joumey to drive. the rivet out of the holder and to set it in thework. This is preferably accomplished by a pair of slides, one mounted on the driving means and movable therewith, and the other frictionally connected to it. in overlapping relation and adapted to move the holder at the appropriate time. f When the holder engages a stop, then the frictional connection betweenthe two slides permits relative movement between them. The provision of this means contributesin a large. measure to the simplification of the machine and eliminates all cams and other parts necessitated-by cams, and permits the use of a simple crank arm as the-operating means.

In the accompanyingdrawi-ngs illustrating one and the preferred form of the invention,

Figure l is a side elevation of a machine constructed and adapted to be operated in accordance with my invention, the'parts being shown in starting position; 7

Fig. 2; is a front elevation, looking. from right to left in Fig. 1, of the operating instrumentalities in starting position; 1 i i a Fig. 3 is'a view similar toFig. 2, bu't showing the. parts in their respective positions'when the driver has moved downwardly into engagement with the head of the rivet, in the holder;

Fig. 4 is a similar view, but showing the parts in their respective positions at the end of the downward movement in unison of the driver and holder; i r

Fig. 5 is a similar view, but showing the parts in their respective positions at the end of the downward movement of the driver through the holder for driving the rivet out of the holder and through the work and clenching it;

Fig. 6 is a vertical sectional view on an enlarged scale of the upper ends of the inner slide and friction strip for producing downward movement of the holder during a certain portion of the downward movement of the driver;

Fig. 7 is a cross-sectional view of the frictional means, also on an enlarged scale, in Fig. 5;

Fig. 8 is a vertical sectional view 'orian ens.

larged scale on line 88 in Fig. 5;

Fig. 9 is a horizontal sectional view on an enlarged scale on line 53-9 in Fig. 5 I s Fig. 10 is a vertical sectional view also on an enlarged scale on line Ill-40 in Fig. 2; l Fig. 11 is a view on line I I in Fig. 1, show ing one of the holder jaws in elevation, a rivet, and the driver in driving position; I a

Fig. 12 is a vertical sectional view online ,l2--l2 in Fig. 3; I

Figs. 13 and 14 are similar views, showing progressive steps in the driving of the rivet; and" Fig. ;15 is a similar view, showing-the final setting of the rivet in the work.

Referring to Figure 1 ofthe drawings, 15 designates the frame of the machine. fastened, to and supported by a standard or column l6. Fastened to the frame is a head 11. carrying the driving means for actuating the operating instrumentalities mounted on the frame. In bearings l8 on the head I! is rotatably mounted a main shaft 20. On the rear endof said shaft is mounted for free rotation thereon, a pulley 22. which constitutes the driving member of a twopart clutch," the other or driven member 23 of which is, fastenedto the shaft 20. The two are clutched togetherto operate as one piece. by 'treadle-operated means hereinafter. described. 7 For driving the rivets during the setting operation, a driver 28, preferably of tapered form, is fastened in the lower end of .aslide or ram 29, guided in ways in a projecting top portion 3! of the frame I5, the slide being held in said ways by a front plate 32 bolted to the portion 3! (Fig. 2). A vertical .reciprocatory motion isirnparted .to the slide 29 by the main shaft through an arm 35 fastened'to its forward'end and a link 33 pivotally connecting the free end of said arm to thesaid slide. On each revolution of. the main shaft, a complete cycle of vertical reciprocation is z a limited vertical reciprocation in ways 43 in the portion 3| of the frame l5 andhleld therein'by a side plate 44. The holder consists of two rivet- The holder is car-T .in cross-section to fit between the holder plates,

on line 1-1 3 and their lower portions are preferably semi-cirholding elongated members or jaws 45 and 46,1

which are loosely supported betweena'nd partially enclosed by holder plates and 48, which are loosely mounted on a pin 49, which, in'turn, isi mounted transversely through a block formed on the lower end of the'holder slide 42. Each holder plate is provided on its inner face with a vertical rib 5f whichprojects into a cor- The holder plates are of rectangular form and project forwardly beyond the block 50, having their forward ends 54 (Fig. 9) turned inwardly to partially enclose the space in which the jaws are mounted. The jaws 45 and 46 are loosely suspended on and between the plates and each is provided with a pair of projecting side ribs 56 and 51 spaced apart for overlapping the top and bottom edges of --its respective plate forpreventing vertical movement of the jaw in relation to the plate.

The upper portions of the jaws are rectangular cular in cross-section. In their engaging faces,

thetwo jaws are each provided with a longitudinal groove or channel 60 semi-circular in crosssection, which opens out the upper end of the jaw through an expanded beveled opening BI and out the lower end of the jaw through a restricted beveled opening 62. When the two jaws are in engagement with each other, the two groovestogether form a. long vertical chamber suitable for housing a long shank rivet. Along their forward vertical edges, the two jaws are cut out'or recessed to form a vertical opening 64 into the said chamber, which opening extends from adjacent the bottom end of the chamber to and out its top end for permitting a long shank rivet 65 to pass from the raceway into said chamber. Since the chamber is normally of slightly smaller diameter than the head 66 of the rivet, the rivet, when delivered from the raceway, is suspended by its head in the expanded top opening of the said chamber in position to be driven. To facilitate the delivery 'of the rivet, the jaws arc'cut' away at 61 and the holder plates at 68 (Fig.11).

the two jaws in engagement with each other, a pressure plate 15 is loosely mounted on each end "of the pin 49, and each plate is pressed inwardly -bya helical spring 76 controlled bya nut 11 threaded on the end of the pin. Each pressure plate is, on its inner face, provided with means for transmitting the pressure of the spring to its respective holder plate and respective jaw. One 'form of this means comprises a plurality of projections or feet, preferably three in number, two of which 18 bear against a holder plate, and the other of which 19 is elongated and extends through a hole in a holder plate and 'bears against one ofthe jaws. Preferably,'the foot 79 is so'positioned on each pressureplate as to engage its respective jaw approximately midway the ends thereof, so that the pressures which tend to hold the jaws closed are transmitted to the jaws midway their ends, permitting the jaws to .fulcrum atthose points when they are opened either at the top or at the bottom.

For producing a differential movement of the driver and holder, I provide means, operable after the driver has moved downwardly close to the rivet, for moving the holder downwardly in unisonwith the driver until the holder is close to the work, and then moving the driver alone to drive the rivet through and out of the holder into the work. One form of this means comprises two vertical slides 83 and 84, the former being fastened at its upper end to a-short arm 85 secured to the top end of the driver slide 29, and the latter being mounted on. the former in overlapping frictional engagement therewith (Fig. 5). The slide 84 is designed to control the movement of the holder, and for that purpose, it is frictionally fastened tothe slide 03 so that it moves as a unit with that slide until such time as its movement is opposed by a force sufficient to overcome the frictional engagement between the slides and to permit relative movement between them.

For holding the slides in frictional engagement, they are enclosed by two blocks 85 and 86 (Fig. 7), held together bya pair of pins 81 carried by the block 85 (Fig. 7). The block 86 is loosely mounted on the pins and is forced inwardly by a pair of springs 88 on the pins, the pressure of which may be regulated by nuts 80 threaded on the outer ends of the pins. On their inner faces, the two blocks are recessed to partially enclose the respective slides, and for holding the blocks in vertical position on the slides, the back face of the slide 83 is provided with a shallow recess 90 (Fig.6) into which the block 85 fits. Preferably, in order to increase the friction between the two slides, a frictional member in the form of a thin strip 9| of fibre or other suitable friction material may be interposed between the two slides, and this strip is fastened at its upper end by the nut 92 fastening theslide 83 to the lateral arm (Fig. 6). proper lateral relation, the slide 83 may be provided with a longitudinal recess for holding the strip 9| and the slide 04.

'For moving the holder member at the proper time, the slide 84 is provided in its lower end with a longitudinal slot 93 through which projects a pin 94 mounted in the holder slide, the length of this slot being of the same length as the preliminary movement of the driver from starting position to driving position with respect to the head of the rivet. For determining the length of movement of the holder slide, the plate 44 is provided with a vertical slot 95 through which the pin 94 projects, which is of the same length as the path of movement of the rivet holder (Fig. 5). This slot serves to limit the movement of the rivet holder in both directions. In the return upward movement of the parts, the frictional engagement between the two slides will generally be sufficient to return the holder to its proper starting position, but to insure this result, a spring 91 under tension may be connected at its top end to a pin 98 set in the top end of the To maintain the two slides in slide 84, and at its bottom end to the pin 94. I

The spring also serves to prevent the holder from starting downwardly prematurely.

In alignment with the holder and driver, in the bored end of an arm I fastened by bolts I01 to the frame I of the machine, is a combined work support and anvil I03. The anvil is supported by a screw I04 threaded into the bottom end of the bore and the verticaladjustment of the anvil. may be regulated by manipulation of the screw (Fig. A set nut I05 holds the screw'in adjusted position. The anvil is provided with an interior bore openingout its bottom end, in which is mounted a hollow member I06 provided on its upper end with a pilot I07, which is held projected through an opening in the top of the anvil for registering the work thereon. A light helical spring I09, under compression, holds the pilot in projected position, yet permits its retraction into the anvil I03 when the rivet is driven into the hole in the work.

Any suitable mechanism may be employed for clutching together thedriving member 22 and the drivenmember 23 for operating the machine, and one such is shown, in which a spring-pressed dog I I 2 mounted on the driven member, is adapted to engage one of a plurality of pins (not shown) carried by the driving member. Normally, the two parts are'held in disengaged position by a slide H4 which engages the end of the dog to hold it out of pin-engaging position. The driving member thereupon turns freely. The slide H4 is mounted for reciprocation in a suitable way formed in the back face of a plate I I5 fastened to the head I! of the frame by screws H6, and is held in forward locking position by a spring I I8 fastened at one end to a pin I I9 set in the plate, and at its other end toza projecting lug I on the rear end of the slide.

For moving the slide'44 out of engagement with the dog II2 to permit the driven member to be clutched to the driving member for starting the machine, a bell-crank lever I22, pivotally mounted on a pin I23 set inthe plate I I5, carries on its upper arm a pawl I25 adapted to engage the lug I20 on the slide and has its lower arm connected toa treadle I26 by a rod I21. The pawl is held in slide-engaging position by a spring I28 under tension, connected at one end to a pin "Meet in the tail of the pawl, and on its other end, to a hook I3I on the bell-crank lever. The pin I30 also serves as a stop engaging one side edge of the lever to hold the nose of the pawl in operative position for moving the slide to the right when the lever is turned by depressing the treadle. In this operation, the nose of the pawlengage's theslide' and moves it to the right until the tail of the pawl strikes a. screw I33 threaded in a projecting lug I34 on the frame, when. the further movement of the lever causes the nose of the pawlto slide off the lug I20, permitting the spring to returnthe slide instantly to operative position for disconnecting the two parts of the clutch at the end of one complete revolution. For a more complete description of the" clutch, reference may be made to United States Letters Patent No. 2,045,550, issued to me on June 23', 1936, for Riveting machine.

In Figures 5, 14 and 15, there is shown in section, tobetter illustrate the operation of the machine, a sample of the Work for which the machine is designed, comprising two pieces. of material I40 and MI which are to be riveted together. These pieces are provided with a bored hole I42 for receiving a long shank rivet 6'5 and the work is positioned on the anvil. I03 with the pilot I01 in thehole.

In the operation of the machine, the depression of the treadle operates the clutch to start the machine. At this time, the parts are in the position shown in Figur s l and 2. The rotation of the main shaft first causes the driverto move downwardly into engagementwith the head of the rivet (Figs. 3, 11. and 12'), which has previously been fed from the hopper andis hanging by its head in the top of the holder. During this first movement, the holder has remained stationary, since the downward movement of the slide 04 produces no effect on the holder, due to the slot 93. In the continued downward movement of the driver, however, the holder is moved downwardly in unison with it through the instrumentality of the slides 83 and 84. The frictional engagement between these slides is suflicient to produce a downward movement of the holder slide and the holder without relative movement between the two slides, until the pin 94 reaches the bottom end of the slot 95, as shown in Figure 4, when the movement of the holder ceases.

The driver then continues its downward movement into the holder, forcing the head of the rivet into the rivet chamber, and, thereby, slightly spreading the jaws apart at their upper ends. The jaws are thereby fulcrumed on the spring-pressed feet midway their length, which tends to hold the lower ends of the jaws in still tighter engagement. In Figure 13, the driver is shown as having entered the holder and pushed the rivet downwardly until the end of its shank is about to enter the restricted opening in the bottom of the holder. At this time, the driver, due to its tapered form, has spread the two jaws slightly apart at their upper'ends; but they are both in engagement with the head of the rivet. The shank of the rivet is then pushed out the bottom opening in the holder, spreading the jaws apart to a slight extent at their bottom ends, but the spring-pressed feet continue to press the two jaws inwardly toward each other to maintain a constant pressure upon both the shank of the rivet and its head as it is driven downwardly out of the holder. As the shank of the rivet passes out of the holder, it entersthe bored hole in the work and follows down through the work, pushing the pilot into the anvil until the end of the driver pushes the head of the rivet through the bottom opening in the holder and causes the lower end of the rivet to impinge against the anvil and to be clenched on the bottom face of the work. At this point, as shown in Figure 15, the jaws have been pressed apart until they are in engagement with the holder plates.

During the downward movement of the driver through the holder, the slide 84 remain stationary, due to the fact that the pin 94 is in engagement with the bottom end of the slot 95 in the fixed plate 44, and the slide 83 moves downwardly in relation to the slide 84 into the final posithe driver is then withdrawn from the holder and raised thereabove to starting position, as shown in Figure 2. If the friction between the driver and holder is not sufficient to move the holder upwardly with the driver, then the frictional engagement between the two slides 83 and 84 will be suflicient to produce the movement in unison, until such time as the pin 94 engages the upper end of the slot 95, when further upward movement of the holder is stopped. The driver then continues its upward movement to starting position, whereupon the machine stops at the end of a complete revolution.

It will be observed that when the jaws are in closed position, they are centered by engagement with the vertical centering plate!!! and the inturned ribs 12 on the ends of the holder plate. This insures proper positioning of the jaws to receive the rivet from the raceway and also positive alignment of the rivet in the holder with the work and anvil. In the absence of these centering means, any difference in the amount of pressure exerted by the two springs upon the jaws would tend to hold them'out of an exact central position in the holder and out of alignment with the raceway and anvil. It may be pointed out also that by making the jaws and the centering plate and ribs of hardened metal, wear on these parts is, to a. great extent, eliminated, and the remaining parts of the holder, including the slide, may be made of ordinary metal, thereby reducing the cost of making these parts, and avoiding the diificulties which would be encountered in hardening the holder slide.

One advantage of using a tapered driver, which in this particular embodiment is necessary for spreading apart the jaws at their upper ends, is that the strength of the driver is greatly increased, which is an important consideration in driving heavy, long-shanked rivets in the kind of work designed to be done by the machine.

It is to be understood that my invention is not to be limited to the precise form herein shown and described, since it may be embodied in other forms of construction within the scope of the following claims.

What I claim is:

1. In a riveting machine, having a rivet driver, a rivet holder including a pair of elongated jaws having confronting faces provided with longitudinal grooves forming a rivet holding chamber, means supporting said jaws in position for said driver to pass therebetween and drive a rivet out of said chamber, and spring means engaging the remote faces of said jaws midway of the ends of said jaws and yieldingly holding said jaws pressed toward each other.

2. In a riveting machine, having a rivet driver, a rivet holder including a pair of elongated jaws having confronting faces provided with longitudinal grooves forming a rivet holding chamber, means supporting said jaws in position for said driver to pass therebetween and drive a rivet out of said chamber, and spring means having rocking engagement with the remote faces of said jaws midway of the ends of said jaws and yieldingly holding said jaws pressed toward each other with capability of relative tilting motions about such engagements.

3. In a riveting machine, the combination with a rivet driver, of a rivet holder comprising a slide, a pair of holder plates loosely mounted on opposite sides of said slide and having their forward end portions turned inwardly, a pair of elongated jaws loosely mounted on and between the forward ends of said plates and back of said inwardly turned portions, said jaws having longitudinal grooves in their engaging faces forming a rivet-holding chamber opening out the top of said jaws through an expanded opening and out the bottom through a restricted opening, and resilient means for holding said plates in close engagement to said slide and for applying pressure to said jaws at points midway their ends to force them toward each other yet permitting them to fulcrum on said points to maintain a constant pressure on the head and shank of a rivet for insuring its travel in a straight path when driven through the holder into the work.

4. In a riveting machine, the combination with .a rivet driver slide and a rivet holder slide, both mounted for vertical reciprocation and means for limiting the path of movement of said holder slide, of means for moving said holder slide in unison with said rivet driver slide during an intermediate portion only of the downward movement of said rivet driver slide, said means comprisingz a pair of slides inoverlapping relation, a frict on lmemb n e media th 1 verl ppin portio s o sa d; ides an resi nt means pr holdingsaid parts in frictional engagement; one of said slides being fastened to. said driver slide and the other being adapted to move said holder slide-'1 ,j'

5. In a riveting machine, the combination with a tapered rivet driver of a rivet holder comprising a slide mounted for vertical reciprocation, a pair of spaced apart holder plates mounted on the lower end of said slide, said plates projecting laterally from said slide and each having an opening therethrough, a pair of elongated jaws having longitudinal grooves in their engaging faces for forming a rivet-holding chamber open at both ends, said jaws being loosely mounted on and between the projecting ends of said plates, said jaws and plates having parts cooperating to lock said jaws against vertical movement in relation to said plates while permitting said jaws to move toward and from each other, and resilient means for holding said plates in engagement with said slide, said means having pressure applying elements extending through the openings in said plates and engaging said jaws at points midway their ends for forcing said jaws together, said elements serving as fulcrums for'rocking engagement with said jaws for maintaining a constant pressure by said jaws on the head and shank of the rivet for insuring its travel in a straight path as it is driven out of the holder and set in the work.

6. In a riveting machine, the combination with a tapered rivet driver of a rivet holder comprising a slide mounted for vertical reciprocation, a pair of spaced apart holder plates mounted on the lower end of said slide, said plates projecting laterally from said slide and each plate having an opening therethrough, a pair of elongated jaws having longitudinal grooves in their engaging faces for forming a rivet-holding chamber open at both ends, said jaws being loosely mounted on and between the projecting ends of said plates, said jaws and plates having parts cooperating to lock said jaws against vertical movement in relation thereto while permitting motion of said jaws toward and from each other, a pair of springs for holding said plates in close engagement with said slide, a pair of pressure plates having parts extending through said openings for transmitting pressure from said springs through the openings in said holder plates to said jaws at points midway their ends for forcing said jaws together, said pressure plate parts serving as fulcrums for maintaining a constant pressure by said jaws on the head and shank of the rivet for insuring its travel in a straight path as it is driven out of the holder and set in the work, and a vertical plate between said jaws and said slide for centering said jaws between said holder plates.

7. In a riveting machine, the combination with a rivet driver slide and means for reciprocating said slide vertically, of a rivet holder slide mounted for vertical reciprocation, and means carried by said driver slide for reciprocating said holder slide during an intermediate portion only of the reciprocation of said rivet driver slide, said means comprising a depending slide bar carried by said driver slide, a second slide bar mounted on said depending slide bar with its upper portion overlapping the same longitudinally and having a vertical slot in its lower end, means for holding said slide bars in frictional engagement,

said, meansbeing; adjustableto vary the force required tor moving them relatively to eachother in' -a longitudinal direction, a fixed member adja cent said holder slide, .said member having a vertical slot equal inlength-to the path of movement of the holderslide, and a pin fixed in said holder slidega-nd-projecting through the slot in said fixed member and into the vertical slot in said second slide bar.

8. In a riveting machine, the combination with a rivet driver slide and means for reciprocating said slide vertically, of a rivet holder slide mounted for vertical reciprocation, and means carried by said driver slide for reciprocating said holder slide during an intermediate portion only of the reciprocation of said rivet driver slide, said means comprising a depending slide bar carried by said driver slide, a second slide bar mounted on said depending slide bar with its upper portion overlapping the same longitudinally and having a vertical slot in its lower end, a friction member intermediate said slide bars, means for holding said slide bars and friction member in frictional engagement, a fixed member adjacent said holder slide, said member having a vertical slot equal in length to the path of movement of the holder slide, and a pin fixed in said holder slide and projecting through the slot in said fixed member and into the vertical slot in said second slide bar.

9. In a riveting machine, the combination with a rivet driver slide and means for reciprocating said slide vertically, of a rivet holder slide mounted for Vertical reciprocation, and means carried by said driver slide for reciprocating said holder slide during an intermediate portion only of the reciprocation of said rivet driver slide, said means comprising a depending slide bar carried by said driver slide, a second slide bar mounted on said depending slide bar with its upper portion overlapping the same longitudinally and having a vertical slot in its lower end equal in length to the length of the preliminary movement of said rivet holder slide, a friction member intermediate said slide bars, means for rivet set, a ram for reciprocating said set, rivet holder supporting means, a rivet holder supporting means actuator operatively connected to said rivet holder supporting means for actuating the same, rivet holder moving means having an operative connection with said ram, said rivet holder moving means and actuator being reciprocable in parallel paths, being in overlapping relation, and being spaced from said ram, and a yieldable connection between said rivet holder moving means and said actuator for providing said jaws with a differential movement with respect to said set.

11. In a riveting machine, a rivet holder, a rivet set, a ram for reciprocating said set, rivet holder supporting means, a rivet holder supporting means actuator operatively connected to said rivet holder supporting means for actuating the same, rivet holder moving means having an operative connection with said ram, said rivet holder moving means and actuator being reciprocable in parallel paths, being in overlapping relation and being spaced from said ram, a

spect to said set, and means for limiting the movement of said jaws whereby said rivet holder moving means-moves in unison with said rivet holder during a portion of the'movement of said yieldable connection between saidrivet holder 5 rivet holder moving means.

moving means and said actuator for providing saidjaws with a. differential movement with re- ARTHUR R. HAVENER- 

